1. Field of the Invention
The present invention relates to a rubber composition, a vulcanized rubber composition, and a heat-resistant rubber product (e.g., radiator hose, heater hose, or radiator packing) using the same.
2. Related Background Art
As radiator hoses, heater hoses, and radiator packing, ethylene/.alpha.-olefin copolymer rubber or ethylene/.alpha.-olefin/unconjugated diene copolymer rubber such as ethylene/propylene rubber (EPM) or ethylene/propylene/unconjugated diene rubber (EPDM) has conventionally been in wide use. Here, ethylene/.alpha.-olefin copolymer rubber and ethylene/.alpha.-olefin/unconjugated diene copolymer rubber are used as vulcanized rubber which has been vulcanized with an organic peroxide. In this case, it has been common technical knowledge that a zinc-containing compound such as zinc oxide is used as an essential component compounded in a rubber composition in order to prevent aging. When a rubber composition including a zinc-containing compound is employed as a radiator hose, heater hose, or radiator packing, however, zinc is likely to dissolve in a cooling medium, thereby affecting mechanical systems.